1. Field of the Invention
The present invention relates to a sequence controller capable of performing a desired sequence control by applying into a memory device a program which is made in accordance with a sequence circuit.
2. Description of the Prior Art
The conventional sequence controller, such as that disclosed in U.S. Pat. No. 3,753,243, entitled "Programmable Machine Controller", patented Aug. 14, 1973, examines or compares periodically and sequentially all input conditions (values of the sensor outputs) with the examine commands in accordance with the program.
However, if a group of logical AND functions are examined, as shown in FIG. 9, if the examination result of one of the logical AND functions is not satisfied, the whole operation of the logic AND functions is not satisfied regardless of the conditions of the remaining logical AND functions. If a group of logical OR functions are examined, as shown in FIG. 10, if the examination result of one of the logical OR functions is satisfied, the whole operation of the logic OR functions is satisfied regardless of the conditions of the remaining logical OR functions. Thus, if one of the logical AND functions is not satisfied in a group of logical AND functions being examined, it is not necessary to examine the remaining logical AND functions. In the case of a group of logical OR functions being examined, if one of the logical OR functions is satisfied, it is not necessary to examine the remaining logic OR functions. The examination of the remaining input conditions, as made in the sequence controller disclosed in the U.S. Pat. No. 3,753,243, is not necessary and therefore any opportunity for malfunction during the examination of the remaining input conditions is effectively prevented.